Mine

function mytheme_user_login($form) {
  drupal_add_js('misc/drupal.js');
  
  unset($form['links']);

  //unset($form['submit']);
  $form['submit']['#value'] = "Go";
  $form['name']['#description'] = t('Enter the %s username.', array('%s' => variable_get('site_name', 'local')));
  $form['pass']['#title'] = '';
  $form['pass']['#description'] = '';
  
  return drupal_render($form);
}